Furnace



Aug. 2s, 192s. 1,551,180

E. B. THORNHILL FURNACE Original Filed Jan. 21. 1921 L I INVENToR.

Edwin :B Tl'lmnhll ATTORNEY.

Patented Aug. 2 5, 1925.

UNITED STATES 1,551,180 PATENT OFFICE.

EDWIN B. THOBNHILL, OF HURLEY, NEW MEXICO, ASSIGNOR T0 THORNHILIi-ANDER- SON COMPANY, OF MUSKOGEE, OKLAHOMA, A CORPORATION OF OKLAHOMA.

FURNACE.

Original application filed January 21, 1921, Serial No. 438,957. Divided and this application illed September 11, 1922. Serial No. 587,314.

To all whom t may concern:

Be it known that I, EDWIN B. a citizen of the United States, residing at Hurley, in the county of Grant and State of New Mexico, have invented a new and useful Improvement in Furnaces, of which v same time providing the requisite strength and durability.

This application is a divisionof my application Ser. No. 438,957, filed January 21, 1921, in which the heating means herein shown were disclosed in connection with a furnace for carrying out a process for production of sponge iron and other products. Iy improved heating elements may, however, be employed with advantage in any furrace wherein heating by radiation is desire The accompanying drawings illustrate apparatus embodying my invent-ion, Fig. 1 being a horizontal section, on line 1-1 in Fig. 2, of a rotary hearth furnace'provided with my improved heating elements; Fig. 2 a section on line 2-2 in Fig. 1; Fig. 3 a vertical section on line 3 3 in Fig. 1; and Fig. 4 a vertical section of a modification. Referring to `Figs. 1 to 3, t-he furnace therein shown comprises a rotary hearth 1, mounted to rotate on a vertical shaft 2, and a furnace casing or enclosure 3, which extends over and around said hearth to form a heating chamber 4 above the hearth. Said furnace casing is shown as having an arched shaped roof 5, but it may be of any suitable form and. may be constructed of any suitable material, for example, ordinary brick lined with iirebrick. h.

The shaft 2 for the` rotary hearth may be mounted in suitable bearin s 6 and 7 and may be driven by any suit'a le means, indicated at,8, so as to hearth. Suitable feed means 9 for supplyl ing the material to the hearth, and outlet means 10 for discharging the material from adapted .to heat the interior of the gradually rotate the the hearth, may be provided in the usual manner of rotary bling means, indicatedA at 11 may also be provided for turning over the material and gradually advancing it from the feed means to the outlet. ever, that any other desirable furnace construction may be used. For exam le, as shown in Fig. 4, the hearth may e stationary as indicated at 12 and the rabbling means, indicated Vat 13, may be rotated in the usual manner of such furnaces. In fact, as regards the present invention, the con struction of the hearth and the presence or absence of rabbling means is immateriahmy present invention relating to the construction of the heating means for the furnace hearth furnaces, and rab,

It willbe understood, howchamber, irrespective of the manner in v preferably as straight horizontal tubes of suitable resistant material extendin through the side walls of the furnace, sai

tubes being open at one end for reception of burners 15 and opening at the other end into an outlet chamber 16 communicating Wit-h a stack 17. Said tubes 14 may consist of any suitable refractory material, preferably material of good thermal conductivity, for example, carborundum, or similar material, and are su ported from the 'roof of the furnace cham er or casing in any suitable manner, for example, b passing through openings in blocks 18 w ich interlock with one another and extend'a'cross the furnace chamber in the :form of an arch, said blocks being of suitable refractory material. With the described construction, the heating elements, extending parallel to one another through the heating chamber and over the hearth thereof, are so positioned as to provide for most eifective radiation of heat from said elements on to the material supported on the hearth and the construction and mounting of said elements are such as to durability of the construction.

In the operation of the furnace, the material to be heated is supplied to the hearth or floor of the furnace in any suitable man-l ner, so as to .be exposed to radiation from the heating elements. The heating devices 14 are brought to a hightemperature` by operation of the burners 15, the Haines from which pass Within and through the heating tubes 14 and heat the walls of such tubes so that they become incandescent: the heat being conducted through the walls and radiated from the outer surfaces thereof, part of the heat so radiated passing directly to the material distributed or placed on the hearth and part of such heat being radiated to the top and sides of the heating chamber 4 and being radiated therefrom to the material on vthe hearth. By this means the temperature of the heating' chamber is maintained at the point required for effective and economical heating of the ore or other material; vfor example, in case the furnace is used for iron ore reduction, a temperature of from 950 to 1000 C. may be maintained. i

The source of heat used for radiating heat to the material being treated may be of any suitable character.l Thus, in place of the heating elements above described, I may use electrical heating elements, such as indicated at 20 in Fig. 4, and comprising a conductor of considerable resistance connected in an electrical circuit and enclosed in a tube of refractory material, .preferably carborundum. As an illustration, this conductor is shown as consisting of fra ents of coke, or other form ofcarbon, indicated at 2O and contained within a tube 21 of refractory material suchas carborundum; electrodes 22 and 23 extendin into opposite ends of the tubes 21 and ma ing contact with the high resistance material 2() therein, such electrodes being connected to an electrical circuit for supply of electric current thereto. It will be understood that any number of the heating elements may be provided and that the same may extend over the hearth so as to provide the required strength and A lheat the entire area of the hearth, or the material thereon, to the proper temperature.

What I claim is:

1. In a furnace, a casing formed with a heating chamber provided with means for supporting material to be heated, and heating elements extending through the said chamber and over the material supporting means, so as to heat the material by radiation, said heating elements comprising straight horizontal tubes of refractory material and means for applying heat internally to said tubes.

2. In a furnace, a casing formed with a yheating chamber provided With means for supporting material to be rtreated, and heating means consisting of straight horizontal tubes of carborundum extending through said chamber and over the material supporting means, so as to heatthe material by radiation, and means for heating said tubes internally. i

3. A furnace comprising a casing formed with a chamber adapted to contain the material to be heated and having a roof extending over said chamber, and .heating means for said chamber comprising a plurality of straight horizontal carborundum tubes extending through the Walls of said chamber, means connected to the roof of the chamber for supporting said tubes, and means for heating said tubes internally.

4. In a furnace, a casing formed with a .heating chamber and with an outlet chamber at one end of said heating'chamber, a plurality of straight horizontal heating tubes extending through said chamber and open at both ends, one end of each of said tubes communicating with the outer air and the other end communicating with the said outlet chamber, burner means adapted to direct hot products of combustion into the respective tubes at the open ends thereof, and meansfor supporting material to be heated below said tubes so as to be heated by radiation therefrom.

In testimony vvhereoi:` I have hereunto subscribed my name this 28th day of August,

EDWIN B. THORNHILL. 

